Pump impellers

ABSTRACT

An impeller blank of conventional design, has its blade geometry altered by trial and error to create a blank of substantially higher efficiency and one which can be trimmed to meet a wider range of power requirements without any material change in such higher efficiency. The physical requirements of the new blank are defined in the specification by empirical formulae.

United States Patent [191 Woell, Jr.

[4 1 Jan. 8, 1974 PUMP IMPELLERS [75] Inventor: Fred T. Woell, Jr., Little Rock, Ark.

[73] Assignee: Jacuzzi Bros. Incorporated [22] Filed: Dec. 15, 1972 [21] Appl. No.: 315,296

[52] US. Cl. 416/223 [51 Int. Cl. F04d 29/38 [58] Field of'Search 416/223, 188, 228

{56] References Cited UNITED STATES PATENTS 1,088,883 3/1914 Donath 416/223 UX 2,599,598 6/1952 Wirkkala 416/228 Wirkkala 416/228 Kondo 416/223 Primary Examiner-Everette A. Powell, Jr. Att0rney-Edward Brosler [57] ABSTRACT An impeller blank of conventional design, has its blade geometry altered by trial and error to create a blank of substantially higher efficiency and one which can be trimmed to meet a wider range of power requirements without any material change in such higher efficiency. The physical requirements of the new blank are defined in the specification by empirical formulae.

2 Claims, 5 Drawing Figures PATENTEDJAN 81914 3,784,321

SHEEI 10? 2 saw an; 2

PATENIE JAN 81974 FIG. 5

HP of MAX.)

1 PUMP IMPELLERS My invention relates to impeller type pumps and more particularly to the impeller component thereof.

In the prior art design of impellers, certain conventional procedures are followed to obtain a blank, the blades of which are then trimmed to conform to the power requirementsunder which it is to function. The efficiency of such blank is of the order of 70 percent and lends itself to trimming while maintaining efficiencies of that order, but only in a relatively narrow range of power ratings, beyond which the efficiency drops off relatively rapidly.

Among the objects of my invention are:

1. To provide a novel and improved impeller blank of substantially increased efficiency over a comparable blank designed in accordance with prevailing practice;

2. To provide a novel and improved impeller blank which enables trimming to conform to wide range of power requirements without appreciably altering efficiency;

3. To provide a novel and improved finished impeller ofhigher efficiency than obtainable in accordance with conventional design procedures.

Additional objects of my invention will be brought out in the following description of a preferred embodiment of the same, taken in conjunction with accompanying drawings, wherein;

FIG. 1 is a view in outline of a jet power plant to which the impeller of the present invention is particularly applicable;

FIG. 2 is a three-dimensional view of an impeller blank of the present invention, as viewed from one end and depicting dimensional variables employed in the design of the impeller blank of the present invention, that is prior to trimming of the same for application in a jet pump, for example, as depicted in FIG. 1;

FIG. 3 is a view in section through the impeller blank of FIG. 2 and depicting some of the dimensions to be considered in its design;

FIG. 4 is a view depicting inner and outer limiting surface factors in the design of the impeller of the present invention;

FIG. 5 is a graph comparing the efficiences obtainable with the present invention with efficiences attributable to impellers of the prior art.

The impeller 1 of the present invention is particularly applicable to jet propulsion, and when so employed,

would be installed in a power plant as depicted in FIG.

1, wherein, the impeller is located within a bowl 3, bolted to a suction piece 4 curving downwardly to the bottom of a boat where it would be exposed to the water for intake to the impeller. From the impeller, the waterwould be discharged through a nozzle 5 as a jet stream which would be directed through the transom of the boat for propulsion purposes.

The impeller blank.7 of the present invention, unlike most inventions, has been derived by trial and error through experimental modification of an .impeller blank of conventional design, resulting in the discovery that a blank having built into it, certain empirical dimensional requirements and relationships, will not only have an efficiency substantially higher than that of a blank of corresponding type, designed in accordance with conventional practice, but the blank may be trimmed to conform to a wide range of power requirements without substantial change in efficiency from 2 one end of the range to the other, this being in direct contrast to a blank of conventional design which, when trimmed, will hold efficiency over a relatively narrow range of power ratings, and with said range being substantially under the efficiences realized by the present invention.

The experimental modifications referred to, were made utilizing a 12 inch blank of conventional design of an open type impeller involving a hub 8 and a plurality of like blades 9. Through trial and error, the blade geometry was changed bringing about a decided increase in efficiency of the blank over the conventional blank on which the changes were made. By correlating the empirical values thus derived, it was found that each impeller blade would be characterized as having a three dimensional pumping surface 11 defined, within a .002272 standard deviation, by the following relationship 1.2 3.2841 2.5365R .93335R .096l59R (.33444 .33759R .10213R .OlOl72R) 6+ (.011248 .0l028lR .0030388R .O0O29756R 0 (.00009'7094 .00008766R .000025673R .0000024867R 0 and having a three dimensional trailing surface 13 described, within a .0005393 standard deviation, by the relationship:

2. Z,= (.84779 1.0602R .41241R .037l68r (.048156 .0087715R .0037763R" .00O52592R 6+(.00088366 .0007l955R .00025916R 00002705812 6 +(.0000048644 .0000049009R .0000017692R .00000017381R) 0 said relationships existing within the four corresponding approximate bounding surfaces of each blade; an outside radius (R defined by the following relationship:

3. R 5.] l9l63 .3346 Z; an inside radius or hub (R,) defined by the following relationship;

a radius (R,,) at the fluid exit, defined by the following relationship;

5. R,,=2.0l0+2.0057 Z; and a radius (R,.) at the fluid entrance defined by the following relationship;

6. R 1.7587 .47355 Z- .25693 Z .085349 Z In the aforementioned relationships,

Z Axial distance from the Z D reference plane to a point on the impeller surface (inches), this Z 0 plane being designated in the drawings by the plane Z Z.

R Radial distance from the centerline axis 15 of the impeller to a point on the impeller surface (inches), r

0 Angular displacement from the 0 0 reference plane to a point on the impeller surface (degrees), such 0 0 plane being designated in the drawings by the plane 0 6.

And the subscripts:

L leading or pumping surface 11 of a blade t= trailing surface 13 of a blade 0 outside edge surface 17 of a blade i hub surface or inside edge 19 of a blade x exit of impeller blade e entrance side of impeller blade As previously indicated, an impeller blank satisfying the blade geometry defined by the foregoing formulae, not only exhibits a much higher efficiency than a blank of conventional design, but may be trimmed over a wider range of power requirements without any marked change in efficiency.

This is amply depicted in FIG. 5 of the drawings wherein the efficiency curve 21, allowing for manufacturing tolerances, shows that a conventional impeller blank of around 175 hp. rating and representing on the chart, a maximum of 100 percent hp. rating, has an efficiency of around 72 percent. As the blades are trimmed to meet power requirements of the order of 95 percent of maximum hp., a slight rise in efficiency to around 74 percent is realized. Beyond this, as the blades are further trimmed to match lower power requirements, the efficiency begins to drop off rather quickly, such that at 60 percent of maximum hp. rating, the efficiency will have dropped off to around 62 percent.

A blank fabricated to satisfy the foregoing empirial formulae, will bring about a blank of 100 percent maximum hp. rating which will have an efficiency of the order of 83 percent. When trimmed to lower power reatings, its efficiency will remain high over a wide band of power ratings, such that when trimmed to a power rating of60 percent of maximum hp. rating, its efficiency will be of the order of almost 80 percent.

Thus, the blank of the present invention surpasses the efficiency of the conventional blank by around 1 l percent, and when trimmed down to one having a rating of 60 percent of maximum hp., its efficiency will exceed that of the conventional impeller by around 17 or 18 percent. These values are merely illustrative of the advantages to be derived from the present invention.

I claim:

1. An impeller blank having a plurality of link blades characterized by each blade having a three dimensional pumping surface 11 defined, within a .002272 standard deviation, by the following relationship:

1.2,, 3.2841 2.5365R .93335R .096159R (-.33444 .33759R .10213R .010172R (.011248 .010281R .0030388R .00029756R) 0 (-.000097094 .00008766R .000025673R +.0000024867R) 0" a three dimensional trailing surface 13 described, with 4 a .0005393 standard deviation, by the relationship:

2. Z (.84779 1.0602R .41241R .037168R) (.048156 .0087715R .00377631? -.00052592R 0 (.00088366 00071955R .00025916R .000027O58R 0 (.0000048644 .0000049009R .0000017692R -(.000000l7381R 0 said relationships existing within the four corresponding approximate bounding surfaces of each blade; an

outside radius (R defined by the following relationship;

an inside radius or hub (R )defined by the following relationship;

a radius (R,) at the fluid exit, defined by the following relationship;

and a radius (R,,) at the fluid entrance defined by the following relationship;

wherein,

Z= Axial distance from the Z 0 reference plane to a point on the impeller surface (inches), this Z 0 plane being designated in the drawings by the plane 2 Z.

R Radial distance from the centerline axis 15 of the impeller to a point on the impeller surface (inches),

0 Angular displacement from the 0 0 reference plane to-a point on the impeller surface (degrees), such 0 0 plane being designated in the drawings by the plane 0 0.

And the subscripts:

L leading or pumping surface 11 of a blade 2 trailing surface 13 of a blade outside edge surface 17 of a blade i= hub surface or inside edge 19 of a blade x exit side of impeller blade e entrance side of impeller blade.

2. An impeller blank in accordance with claim 1,

characterized by said blades being trimmed to provide a lower power rating. 

1. An impeller blank having a plurality of link blades characterized by each blade having a three dimensional pumping surface 11 defined, within a .002272 standard deviation, by the following relationship:
 1. ZL 3.2841 - 2.5365R + .93335R2 - .096159R3 + (-.33444 + .33759R - .10213R2 + .010172R3) theta + (.011248 - .010281R + .0030388R2 - .00029756R3) theta 2 + (-.000097094 + .00008766R - .000025673R2 +.0000024867R3) theta 3 ; a three dimensional trailing surface 13 described, with a .0005393 standard deviation, by the relationship:
 2. An impeller blank in accordance with claim 1, characterized by said blades being trimmed to provide a lower power rating.
 2. Z4 (.84779 - 1.0602R + .41241R2 - .037168R3) + (.048156 -.0087715R + .0037763R2 -.00052592R3) theta + (.00088366 + . 00071955R - .00025916R2 + .000027058R3) theta 2 + (.0000048644 - .0000049009R + .0000017692R2 -(.00000017381R3) theta 3 said relationships existing within the four corresponding approximate bounding surfaces of each blade; an outside radius (Ro) defined by the following relationship;
 2. Z4 (.84779 - 1.0602R + .41241R2 - .037168R3) + (.048156 .0087715R + .0037763R2 -.00052592R3) theta + (.00088366 + . 00071955R - .00025916R2 + .000027058R3) theta 2 + (.0000048644 - .0000049009R + .0000017692R2 -(.00000017381R3) theta 3 said relationships existing within the four corresponding approximate bounding surfaces of each blade; an outside radius (Ro) defined by the following relationship;
 3. Ro 5.119163 - .3346 Z; an inside radius or hub (Ri)defined by the following relationship;
 3. Ro 5.119163 - .3346 Z; an inside radius or hub (Ri)defined by the following relationship;
 4. Ri 2.010 - .45995 Z; a radius (Rx) at the fluid exit, defined by the following relationship;
 4. Ri 2.010 - .45995 Z; a radius (Rx) at the fluid exit, defined by the following relationship;
 5. Rx 2.010 + 2.0057 Z; and a radius (Re) at the fluid entrance defined by the following relationship;
 5. Rx 2.010 + 2.0057 Z; and a radius (Re) at the fluid entrance defined by the following relationship;
 6. Re 1.7587 + .47355 Z - .25693 Z2 + .085349 Z3 - 009182 Z4; wherein, Z Axial distance from the Z 0 reference plane to a point on the impeller surface (inches), this Z 0 plane being designated in the drawings by the plane Z - Z. R Radial distance from the centerline axis 15 of the impeller to a point on the impeller surface (incheS), theta Angular displacement from the theta theta reference plane to a point on the impeller surface (degrees), such theta 0 plane being designated in the drawings by the plane theta - theta . And the subscripts: L leading or pumping surface 11 of a blade t trailing surface 13 of a blade o outside edge surface 17 of a blade i hub surface or inside edge 19 of a blade x exit side of impeller blade e entrance side of impeller blade.
 6. Re 1.7587 + .47355 Z - .25693 Z2 + .085349 Z3 - 009182 Z4; wherein, Z Axial distance from the Z 0 reference plane to a point on the impeller surface (inches), this Z 0 plane being designated in the drawings by the plane Z - Z. R Radial distance from the centerline axis 15 of the impeller to a point on the impeller surface (incheS), theta Angular displacement from the theta theta reference plane to a point on the impeller surface (degrees), such theta 0 plane being designated in the drawings by the plane theta - theta . And the subscripts: L leading or pumping surface 11 of a blade t trailing surface 13 of a blade o outside edge surface 17 of a blade i hub surface or inside edge 19 of a blade x exit side of impeller blade e entrance side of impeller blade. 